Block-signal system.



PATBN'TED SBPTQI, 1908.

L. A. HAWKINS. BLOCK SIGNAL SYSTEM.

APPLIOATION FILED FEB. 19,1908.

LA RENBEJW ATT'IC is? Y WI NEQSEE:

UNITED STATES 1 nrENT OFFICE.

LAURENCE A. HAWKINS, OF SCHENEUTA'DY, NEW YORK, ASSlUNUlt 'IO GENERAL I'ILIXTRIU COMPANY, A CORPORATION 01" NEW YORK.

BLOCK-SIGNAL SYSTEM.

Specification 0! Letters Patent.

Patented Sept. 1, 1908.

Application filed February 19, 1908. Serial No. 416,696.

To all whom it may concern:

Be it known that I, LAURENCE A. HAW.- KINS, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Block-Signal Systems, of which the following is a specification.

My invention relates to alternating-current block signal systems, and its object is to provide a novel-arrangement of such a system, whereby an overlap is obtained in a sim 1e and convenient manner.

y the use ofa roper overlap it is possible to dispense with istant signals. On steam roads, where the traffic consists chiefly of long heavy trains, the overlap is not a satisfactory substitute for the distant signal, since the absence of an indication of the condition of a home signal, until the home signal itself is in sight, frequently results in necessitating an emergency stop. On certain classes of electric roads, however, as, for instance, on interurban lines, where the traflic consists of single cars or short trains, quick stops, instead of being objectionable are the rule in ordinary operation so that the overlap is a satisfactory substitute for the distant signal. Furthermore, long blocksare the rule so that because of the high impedance offered by the trackrails to alternating-current, it is ordinarily desirable to supply the signal current to the rails near the centers of the blocks and to rovide relay connections at both ends of the block. When this is done, my invention renders it possible to obtain the desired overlap on interurban roads without any addition to the apparatus, or to the wiring, and, therefore, wit tional expense whatever.

My invention will best be understood by reference to the accompan ing drawing, which shows diagrammatlcal y an-alternatout any addiling-current block signal system arranged in accordance with my invention.

In theidrawing A A represent the track rails of two blocks of an electric railway, and B represents the third-rail ortrolley-wire.

' The rails A A of the two blocks are insulated power-current .is

from each other, and a return path for the provided in any suitable manner as, for instance, throug reactive bonds (1 C.

D represents the power-generator which is represented diagrammatically as a direct current generator.

1 re resents an alternating-current generator or supplying current for the signal circuits.

F represents line-wires connected to the enerator E, and G G are transformers havmg their primaries connected to the linewires and the secondaries connected across the track-rails near the centers of the blocks.

H, H, H and H re resent track relays, which are shown as of t e two-phase inductive ty e, comprising a secondary member h, a win in it connected to the track, and a winding sup lied directly from the linewires B through suitable phase controlling means indicated by the condenser h.

I I represent home si esent the operating mechanisms and e sources of current therefor.

It will be seen that the operating 0r.con trolling circuit of the si al I extends throu h contacts of relays I-l, 1 and H, so that t e signal is controlled jointly by the relays at both ends of the block which the signal guards, and lso by the relay at the adjacent end of the block next inadva'nce. This con n'eetion of the signal circuit results in iving an overlap of something more-than alf a block in length. If a train is in the block between the relays H and H, one of these relays is short-,circuited, so as to open the signal circuit. When the car or train passes out V of block A' into block A, the signal I is not immediately cleared, although both rela and H close their contacts. The si a suit is open at contacts of the re ay H,

which is now 'short-circuited owin to the resenee of the train between it and t e transormer G. Relay Hremains deenergized and signal'I at danger until the car or train has passed transformer G. a sufiicient distance to allow its secondary volta e to rise sufficiently to energize relay H an cause it to close its contacts. Thus, a positive overlap of something more than half a block in length is obtained without inereasin the number of insulated joints, inductive nds or relays, or the amount of .as come pared with any current is supplied at the centers of the blocks. I do not desire to limit myself to the particular construction or arrangement of parts rails. at both ends of the blocks, and home Signals for the blocks, each of said signals being controlled jointly by the relays at both ends of the block guarded by the si nal and by the relay atthe adjacent end oft e block next in advance.

2. An alternating-current block signal system, comprising sources of alternating-currentconnected to the track rails near the centers of the blocks, relays connected to rails at both ends of each lock home signals, and controlling circuits forthe signals, the controlling circuit of'each of said signals including contacts of the relays at both ends of the block guarded by the signaland of the relay at the adjacent end of the block next in advance.

' 3. An alternating-current block signal system, comprising sources of alternating-current connected to the track rails near the centers of the blocks, track relays, relay conure of alternating-current in the relay connections at either. end of the block guarded by the signal or in the relay connections at the adjacent end of the block next in advance.

4. An alternating-currentblock signal system, comprising sources of alternating-current connected to the track rails near the centers of the blocks, relays connected'to the rails at both ends of each block, and signals for the blocks, the relay at the enterin end of a block being arranged to control the nome signals both for that block and for the block next in the rear.

In witness whereof, I have hereunto set my hand this 18th day of February, 1908.

LAURENCE A. HAWKINS. 

